Portable power distribution cabinet

ABSTRACT

A modular, light-weight, portable electric power distribution cabinet having high structural integrity and being readily adaptable for cost effective use in a wide variety of applications. The cabinet can be arranged to be a main power feed, trunk or branch feed type cabinet and a plurality of cabinets of said type can be selectively coupled to one another to provide a power distribution network of any desired configuration. The cabinet also provides for direct access of power cables to the interior of the cabinet so that cables with lugs at the ends thereof can be directly coupled to a bus feed arrangement within the cabinet. The direct access feature of the cabinet includes a cable clamp door to simultaneously engage and clamp a plurality of lugged cables for ancillary strain relief. The cabinet includes a transparent panel to permit a worker to view the interior of the cabinet without exposure to an electric shock hazard so that the worker can attend to the coupling of the lugged cables to the bus feed arrangement. The transparent panel is provided with small diameter holes for direct insertion of an appropriate tool to engage set screws of the lugs of the lugged cables so that the lugged cables can be fastened to the bus feed arrangement without having to remove any panels from the cabinet.

RELATED APPLICATION

This application is a continuation-in-part of application Ser. No.496,412, filed Mar. 20, 1990, entitled PORTABLE POWER DISTRIBUTIONCABINET AND POWER DISTRIBUTION NETWORK, now U.S. Pat. No. 5,070,429.

FIELD OF THE INVENTION

The present invention is directed to a high capacity, portable electricpower distribution cabinet. More particularly, the present inventionprovides a new and improved modular, light-weight, portable electricpower distribution cabinet having high structural integrity and beingreadily adaptable for cost effective use in a wide variety ofapplications.

BACKGROUND OF THE INVENTION

There are many facilities, buildings, sites and locations that requireelectric power and yet do not have fixed electric power distributionsystems. For example, in the entertainment industry, motion picture andtelevision production studios typically comprise a building shell toprovide an interior that is isolated from ambient light and sound. Thebuilding shell does not contain any fixed internal structures orutilities to afford maximum versatility in the use of the interior ofthe building shell for the construction of sets. As should beunderstood, sets for motion picture productions vary widely from filmproject to film project and the electrical requirements for anyparticular set are not known until the project is scheduled forproduction and the set is designed. Any fixed internal electrical wiringor power distribution equipment would limit the placement of lightingfixtures, technical equipment and other devices, such as special effectsmachines, and, thus, restrict the use of the studio. Accordingly,portable power distribution arrangements are installed to service thepower needs of a particular set and are then removed when the set isstruck.

There are also many other sites and locations having power distributionneeds that vary with time, such as an outdoor site used for travelingcarnivals, outdoor concerts, theme parks and so on. Indeed, there are agreat many locations that require a portable power distribution facilitythat can be easily installed on a temporary basis, configured andreconfigured to any desired network of main power feed, trunk feeds andbranch circuits and conveniently disassembled for storage and/orshipment to other locations. Examples of such locations, in addition tothose discussed above, include construction sites, convention andexhibit halls and any area or location during times of emergency such asearthquakes and the like.

However, presently known components used to provide portable powerdistribution are heavy and massive in size and construction, are notstandardized, and are generally difficult and labor-intensive toinstall. They are also not suitable for convenient handling, storage ortransportation to various sites. For example, the motion pictureindustry typically utilizes heavy panel boards, each containing a mainconnection to a power source. Each panel board includes power outputshaving large machine-screw studs to which lugged cables are attached.Over current protection is generally not provided for any of the branchcircuits fed by the lugged cables. Moreover, the panel boards are solarge and heavy that they require machines to lift and load them into atruck for transportation.

The motion picture industry also commonly utilizes a wiring devicereferred to as a "Sister" lug. A sister lug generally comprises a castbrass lug with a U shaped opening and a set screw. The sister lug istypically soldered to a flexible cable for transmission of electricalpower to or from the lug. In practice, the U shaped opening of thesister lug is received around a cooper conductor bus of a power cabinetinput or output terminal and held in contact with the bus by the setscrew. In this manner, electrical power can be transmitted to and from apower cabinet via an arrangement of cables and sister lugs.

While sister lugs provide a fast, rugged and inexpensive form ofelectrical connector, they pose electrical code compliance problems. Forexample, the set screw of the sister lug arrangement is used to securethe lug to the bus and to provide a good electrical contact between thelug and the conductor bus. Accordingly, as required by, for example, theNational Electric Code (NEC), an ancillary strain relief device must beprovided to relieve any mechanical force applied to the cable solderedto the lug.

Without an ancillary strain relief, mechanical forces would be applieddirectly to the set screw which could cause the electrical connection toloosen. Indeed, if the mechanical force is great enough, the sister lugmay become free from the connector bus. In addition, an electricaloverload on the cables or electrical arcing caused by a loose connectioncan heat the solder connection between the cable and the lug. In somecircumstances, the heat generated can be sufficient enough to melt thesolder connection and free the cable. The use of an ancillary strainrelief device makes certain that the cable is secured in a fixedposition in the event the sister lug loosens or the cable becomesdisconnected from the lug due to, e.g., solder melting.

However, the use of an ancillary strain relief device adds to the amountof labor needed to attach a sister lug to a conductor bus. When manylugged cables must be connected in a power distribution network, thetotal extra labor required for securing ancillary stress relief devicesindividually to each cable in the network can become a considerabledisadvantage in the use of sister lugs. Furthermore, the use ofconventional electrical cable clamps for ancillary strain relief isordinarily not feasible inasmuch as the typical size of a sister lugexceeds the diameter of a conventional cable clamp.

In another known portable power device, generally referred to as a loadsplitter box, several bus bars are mounted on insulators. Each bus baris coupled to a lug-connector input of a heavy feeder cable. C-clamptype lugs are used to connect branch circuit cables to the bus bars andno over-current branch protection is provided for the individual branchcircuit cables. Carnivals often use such load splitter boxes and simplycover exposed electrical connections with a rubber mat. Such loadsplitter boxes are labor-intensive to install and do not accommodate awide variety of electric power applications.

In addition, the lack of over-current protection for each individualbranch circuit coupled to the panel board or load splitter box, ishighly undesirable. For example, a branch overload or short circuit canresult in dangerous cable overloading and resultant fires. There arealso inherent hazardous conditions present in a wire or cable sizereduction, as for example, from the bus bar to branch circuit cable ofthe load splitter box. Such potential hazardous conditions remainunchecked without overcurrent protection for each individual branchcircuit.

Moreover, in many instances, various power distribution units must becoupled to one another to provide a power distribution network. The lackof standardization between known power distribution devices and thevarying approaches to portable power distribution adapted on an"as-needed" basis by those who require portable power distribution, hasleft the industry without a cost-effective, convenient and versatilecomponent suitable to provide a wide variety of network configurationssupplying widely varying electrical needs.

SUMMARY OF THE INVENTION

The present invention provides a light-weight, versatile and portablepower distribution cabinet having a modular design of high structuralintegrity suitable for expedient change of power connectors, powerconnector panels and circuit breakers. In this manner, a single powerdistribution cabinet can be readily adapted to a wide range ofapplications and selectively coupled to other such cabinets for use as amain power feed, trunk feed and/or branch circuit feed within a powerdistribution network.

Generally, the cabinet structure according to the present inventioncomprises end frames, each suitable for manufacture as a single castpiece for structural integrity, and arranged to removably mount an endpanel recessed from the plane defined by the end edges of the end frame.Corner rails extend between the interior corners of the end frames toprovide the side corners of the cabinet. Each corner rail also providescabinet corner forming surfaces and panel receiving surfaces offset fromthe corner forming surfaces for removable mounting of side, top andbottom cabinet panels that are recessed from corners of the cabinetdefined by the corner rails.

Each end and side panel can be arranged to mount a predetermined numberof electrical connectors, each being of a preselected configuration,type and power capacity. The removable mounting of each panel to the endframes or panel receiving surfaces of the corner rails, as the case maybe, provides a high degree of flexibility and versatility to the designof the cabinet according to the present invention. A panel or panelshaving electrical connectors of a type, power capacity, etc. required byan application intended for the power distribution cabinet at theparticular time, can be conveniently mounted to the cabinet.

Those panels can then be removed and replaced with other panels whenanother application, having different connector requirements, isintended. Thus, a single cabinet can be readily equipped with any typeof connector simply by maintaining an inventory of panel membersmounting various different types of connectors and mounting suitablepanels to the cabinet, as required. In addition, the flat metal piecestructure of the panels makes it very cost-effective to maintain such aninventory of panels for connector changes.

Moreover, the recessed mounting of each end, side, top and bottom panel,as described above, affords easy handling and stacking of the cabinets,since the connectors mounted on the panels will also be recessed andtherefor not exposed to contact with connectors of another cabinet in astack or a floor surface. The end frames, panels and corner rails aresuitable for manufacture from aluminum for a light weight, yet durableand rust resistant construction.

One of the panels of the cabinet, typically the bottom panel, isutilized to mount a circuit breaker chassis within the interior of thecabinet to, in turn, removably mount one or more circuit breakers,typically one circuit breaker for each branch circuit connector mountedon the other panels of the cabinet for individual branch circuitovercurrent protection. Another panel of the cabinet, e.g., one of theend panels assembled to an end frame, can be arranged to mounthigh-capacity, main power plug-in type connectors. For example, in athree phase system, there would be one plug-in connector for each phase,a fourth plug-in connector for a neutral terminal of the three phasesystem and a fifth plug-in connector acting as a ground.

A novel bus bar feed arrangement is also mounted within the interior ofthe cabinet to couple each main power plug-in terminal to intermediateconnectors that provide removable couplings to the chassis mountedcircuit breakers, panel mounted connectors and a ground connector. Theintermediate connectors permit the intercoupling of the main powerplug-in connectors to other panel mounted connectors to construct mainpower, trunk and branch circuit feeds, as desired, while facilitatingthe easy removal and replacement of the panels, as well as the circuitbreakers, for a new electric power application.

One of the panels can be arranged to provide direct access to the busbar feed arrangement mounted within the interior of the cabinet so thatcables having lugs, such as, for example, sister lugs, can be directlycoupled to the conductor busses of the bus bar arrangement. The directaccess panel includes openings for insertion of the lug ends of powercables into the interior of the cabinet.

An additional top opening is also provided in the cabinet so that aworker has access to the interior of the cabinet for attaching thesister lugs of the cables to the appropriate busses via the set screwswithout having to remove any of the panels of the cabinet. The openingis protected by a heavy duty, heat resistant, transparent window, suchas, e.g., a transparent plastic panel. In this manner, the worker canview the lugged cables and conductor busses while the interior of thecabinet is isolated from the worker by the plastic window. Accordingly,the transparent panel will prevent electric shock hazard when the cablesare energized. The transparent panel is provided with relatively smalldiameter holes aligned with the set screws of the lugged cables so thatthe worker can insert an appropriate tool to secure the set screws. Thediameter of the holes and the spacing of the transparent panel from thelugged cables are dimensioned to maintain the shock prevention functionof the transparent panel.

Moreover, the direct access panel includes a hinged cable clamp doorthat is arranged to close over the openings for the cables withsufficient clearance between the lower end of the cable clamp door andthe bottom of each one of the openings for placement of the cables.However, the clearance is dimensioned so that the lower end of the cableclamp door engages and clamps the cables between the lower end of thedoor and the bottom of each of the respective openings to provide anancillary strain relief for all of the cables. Thus, the cable clampdoor arrangement can be utilized to simultaneously clamp all of fivecables of, for example, a three phase system, for ancillary strainrelief of the cables in an efficient and expeditious manner.

Thus, each individual cabinet can be adapted to be either a main powerfeed, including a main circuit breaker, a trunk feed and/or a feed to aplurality of branch circuits, each branch circuit including its owncircuit breaker for maximum overcurrent protection throughout thenetwork. The main, trunk and branch arrangements for the individualcabinets provide three basic cabinet types that can be utilized toconstruct a power-distribution network of any configuration.

The portable power distribution cabinet according to the presentinvention is highly modular from the end frame, corner rail cabinetconstruction, removable connector and direct access panels and circuitbreaker chassis to the flexible intercoupling of prearranged main feed,trunk feed and branch circuit power distribution cabinets, to form anetwork of any preselected configuration and operating characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an assembled portable power distributioncabinet according to the present invention.

FIG. 2 is another perspective view of the portable power distributioncabinet of FIG. 1.

FIG. 3 is an exploded perspective view of the portable powerdistribution cabinet of FIG. 1.

FIG. 4 is an end cross-sectional view of an extruded cabinet corner railaccording to the present invention.

FIG. 5 is an end cross-sectional view taken at one corner of anassembled portable power distribution cabinet according to the presentinvention.

FIG. 6 is a top plan view of the interior of the portable powerdistribution cabinet of FIG. 1, arranged as a branch feed type cabinet.

FIG. 6a is a top plan view of the interior of the portable powerdistribution cabinet of FIG. 1, arranged as a trunk feed type cabinet.

FIG. 6b is a top plan view of the interior of the portable powerdistribution cabinet of FIG. 1, arranged as a main power feed typecabinet.

FIG. 7 is an exploded perspective view of a circuit breaker chassismounted to a bottom panel of the cabinet according to the presentinvention.

FIG. 8 is a block diagram illustration of a power distribution networkcomprising an array of portable power distribution cabinets according tothe present invention.

FIG. 9 is a top view of the portable power distribution cabinet of FIG.1 arranged to provide a direct coupling between lugged power feed cablesand the internal bus feed arrangement of the cabinet.

FIG. 10 is a top plan view of the interior of the portable powerdistribution cabinet of FIG. 9.

FIG. 11 is a side, partial cross-sectional view of one of the luggedpower feed cable, bus feed couplings of the portable power distributioncabinet of FIG. 10.

FIG. 12 is a front view of the portable power distribution cabinet ofFIG. 9.

FIG. 13 is a further front view of the portable power distributioncabinet of FIG. 9 illustrating the clamp door of FIG. 12 partially cutaway and in an open position.

FIG. 14A is a side, cross-sectional view of the clamp door arrangementof the portable power distribution cabinet of FIGS. 12 and 13 with theclamp door in an open position.

FIG. 14B is a side, cross-sectional view of the clamp door arrangementof the portable power distribution cabinet of FIGS. 12 and 13 with theclamp door in a closed position.

DETAILED DESCRIPTION

Referring now to the drawings and initially to FIG. 1, there isillustrated a perspective view of a portable power distribution cabinetaccording to the present invention, designated generally by thereference numeral 10. The cabinet comprises a pair of end frames 11assembled to one another by four corner rails 12. Enclosure panels suchas end 13, top 14, side 15 and bottom 17 panels are mounted to the endframe 11 and corner rails 12, respectively and are secured thereto bythreaded screws 16 for easy removal, when desired. Each of the endframes 11 and corner rails 12 is arranged and configured to providepanel receiving surfaces such that each panel 13, 14, 15, 17 is recessedfrom the outermost corner and end surfaces of the cabinet 10, as clearlyillustrated in FIG. 1 and as will be described in more detail below.

A first series of electrical connectors 18 is mounted to the end panel13 and a second series of electrical connectors 19 is mounted to theside panel 15. Each connector 18, 19 can comprise any preselected typeof known electrical connector, e.g., screw type, male-female plug typeor even standard household outlets, of varying power capacities, asdesired by a user. For example, the connectors 18 can comprise highcapacity female plugs for coupling, via plug-in, flexible power cables(not specifically illustrated), to a source of power such as a generatoror to another power distribution cabinet, to provide a trunk feed withina network. The connectors 19 can be lower capacity, 120 V, 60 A plugsfor direct connection to various branch loads, such as lightingfixtures. Any of the panels 13, 14, 15, 17 and the connectors 18, 19mounted thereon can be readily removed from the cabinet 10, byunscrewing the respective screws 16, and replaced by other panelsmounting any other type of connectors, as may be required in anotherelectric power application of the cabinet 10.

Thus, the mounting of the connectors 18, 19 on panels that can bereadily removed from the cabinet 10, provides a modular constructionfacilitating a highly versatile utility for the cabinet 10. Anyconnector type needed by a particular power application can be easilymounted on the cabinet by simple replacement of, e.g., the end 13 andside 15 panels with end 13 and side 15 panels having the requiredconnector type. Moreover, panels 13, 14, 15, 17 are recessed by adimension such that the connectors 18, 19 are also recessed from theoutermost edges of the cabinet 10 to permit stacking of the cabinets 10,particularly while not in use, for storage or shipment, without anyphysical contact between connectors 18, 19 mounted on panels ofadjacent, stacked cabinets 10.

As illustrated in FIG. 1, the top panel 14 can be provided withrotatable, recessed handles 20, for convenient lifting of the cabinet 10and a hinged panel door 21, for easy access to, e.g., individual circuitbreakers switches 23 (See FIG. 2) mounted within the cabinet, as will bedescribed. The top panel 14 can include a switch housing 22 integraltherewith and extending into the interior of the cabinet 10 to exposethe switches 23 through openings 24 formed in the housing 22, forconvenient manual manipulation, while isolating the remaining interiorof the cabinet 10, to prevent exposure to electrical connections.

Referring now to FIG. 3, each end frame 11 comprises a single castaluminum piece including an end frame rail 25 extending as a rectangularrim to provide an outer edge 26 of the cabinet 10 and an interior,corner rail and panel receiving surface 27. Each end frame rail 25defines a rectangular end opening for reception of a respective endpanel 13, as illustrated in FIGS. 1 and 2. The corner rail and panelreceiving surface 27 of the end frame rail 25 includes an integralinterlock rim 28 raised from the corner rail and panel receiving surface27, toward the interior of the cabinet 10, and extending around theentire rectangular extent of the end frame rail 25 at a position spacedinwardly from the outer top, side and bottom surfaces 31 of the endframe rail 25. A pair of end panel receiving surfaces 29 extend, onefrom either side of each raised interlock rim 28, into the rectangularopening defined by the respective end frame rail 25. In this manner, anend panel 13 can be received into the rectangular opening from the outerend 26 until it abuts against the end panel receiving surfaces 29 at aposition recessed from the outer end 26 of the respective end frame rail25. A series of threaded openings 30 is formed through each end panelreceiving surface 29 for threaded reception of the screws 16 toremovably secure the end panel 13 to the end frame 11, as describedabove.

Pursuant to a feature of the invention, each interlock rim 28, by virtueof its raised configuration toward the interior of the cabinet 10 andits position, spaced inwardly from the outer surfaces 31 of therespective end frame rail 25, defines a series of panel receivingsurfaces 32 for support of the end edges 33 (See FIG. 1) of each top,side and bottom panel 14, 15, 17, respectively, recessed from the outersurfaces 31. The panel receiving surfaces 32 are separated from oneanother, at each corner 34 of the respective end frame rail 25, by aninterlock member 35 integrally formed in the interlock rim 28.

As clearly illustrated in FIG. 3, each interlock member 35 comprises apair of corner rail receiving grooves 36, disposed at a 90° anglerelative to one another, and each defining a stop surface 37intermediate the respective groove 36 and the adjacent panel receivingsurface 32. Each groove 36 includes a threaded opening 36a to secure acorner rail 12, as will appear. The interlock rim 28 is formed at eachcorner, intermediate each pair of 90° disposed corner rail receivinggrooves 36, as a generally rectangular solid 38, truncated at two sidesthereof by the grooves 36, to provide an interlock element for receptionwithin and mating with a complimentary end of one of the corner rails12.

Referring now to FIG. 4, each corner rail 12 comprises an extrudedsection of aluminum including cabinet corner forming surfaces 40,disposed at 90° angles relative to one another and dimensioned totightly receive, within the volume defined by the surfaces 40, onerespective interlock element 38. The corner rail 12 also includes a pairof web portions 41, each disposed at a 90° to a respective cornerforming surface 40 and together arranged to surround the truncated sidesof the interlock element 38 and to integrally secure a pair of panelreceiving surfaces 42, each one extending parallel to and offset from acomplementary corner forming surface 40, as illustrated. Each panelreceiving surface 42 is formed to a thickness approximately equal to thedepth of the grooves 36 and is provided with a series of openings 43(See FIG. 3) spaced longitudinally across the surface 42 to removablysecure the panels 14, 15, 17, respectively, to the cabinet 10, by meansof the screws 16 as described above. To that end, each panel is formedto include openings 43a arranged for alignment with the openings 43.

Accordingly, in the assembly of the cabinet 10, each end of each cornerrail 12 is axially applied to a corresponding corner 34 of one of theend frames 11 such that the panel receiving surfaces 42 are eachreceived within a respective groove 36 and the interlock element 38 isreceived within the volume defined by the corner forming surfaces 40 andweb portions 41, until the end of the respective corner rail 12 abutsagainst the corner rail and panel receiving surface 27 of the end frame11. Since each panel receiving surface 42 is of a thickness equal to thedepth of the grooves 36, the panel receiving surfaces 42 at oppositecorners of each end frame 11 will each be flush with the adjacent panelreceiving surface 32 of the interlock rim 28, extending therebetween, toprovide a continuous, recessed panel receiving surface from side-to-sideof each side of the end frame 11.

Moreover, outer edges 44 of each panel receiving surface 42 will abutagainst the stop surface 37 of each respective groove 36. The abutmentbetween the stop surfaces 37 and outer edges 44 of the respective panelreceiving surfaces 42, the contact between the panel receiving surfaces42 and the grooves 36, the contact between four outer surfaces of therectangular solid interlock element 38 and the respective interiormating surfaces of the corner forming surfaces 40 and web portions 41,as well as the abutting contact between the end edge of the corner rail12 and the corner rail and panel receiving surface 27 of the end frame11, together provide a nine surface, multi-planar interlock between eachcorner rail 12 and the complimentary interlock member 35 of the endframe 11 for a high degree of structural integrity.

Each corner rail 12 can be secured at the corner interlock by a screw 16received into openings 43 formed through the corner rail 12 at positionsarranged to align with the threaded openings 36a of the grooves 36. Whenall four corner rails 12 are each interlocked with respective, opposedcorners 34 of opposite end frames 11, a cabinet frame is provided forreception and mounting of the end, top, bottom and side panels 13, 14,15, 17 to complete the cabinet construction.

Referring to FIGS. 3 and 5, each panel receiving surface 42 extends fromside-to-side of one corner side defined by a respective corner rail 12within the cabinet frame formed by the corner rails 12 and the endframes 11. Moreover, due to the flush relation between the panelreceiving surfaces 42 of the corner rails 12 and the panel receivingsurfaces 32 defined by the raised interlock rims 28, as described above,a complete recessed rectangular panel receiving surface is formed aroundthe entire perimeter of each of the top, bottom and each side of thecabinet 10. Thus, each panel 14, 15, 17 can abut against and beremovably secured to a respective side, top or bottom of the cabinetframe by threaded engagement between the screws 16 and aligned openings43, 43a to form the cabinet 10. Of course, as described above, the endpanels 13 are mounted to the panel receiving surfaces 29 of the endframes 11.

Referring now to FIGS. 6 & 7, there is illustrated the interior of anassembled cabinet 10 according to the present invention. As describedabove, the panels of the cabinet 10 mount various preselected electricconnectors, e.g., connectors 18, 19, to provide a desired connectivityas a main power feed, trunk feed and/or branch circuit feed. Theinterior of the cabinet 10 is provided with a bus feed arrangement 100and circuit breaker chassis 101 for selective, removable intercouplingof the panel mounted connectors with each other.

For example, each connector 18 mounted on one of the end panels 13 ofthe cabinet 10, can comprise a high capacity, plug-in type connectorhaving a threaded terminal 102 on the interior side of the cabinet 10.For coupling to a three phase electric system, five connectors 18 aremounted to the end panel 13, one for each of the three phases, a neutralterminal and a ground terminal.

The chassis 101 is mounted on the bottom panel 17 within the interior ofthe cabinet 10, and is illustrated in exploded form in FIG. 7. Thechassis 101 provides, e.g., a mounting for two side-by-side arrays ofcircuit breakers 103, each removably received into the chassis 101.Generally, the chassis 101 comprises four corner support elements 104,each having mounting tabs 105 for mounting to the panel 17, as forexample by screws (not specifically illustrated). Each pair of supportelements 104, on one side of the chassis 101, support a breaker mountingrail 106 therebetween. The breaker mounting rails 106 are each formed toinclude a plurality of tabs 107 spaced along the length of the rail 106between the respective support elements 104. Each circuit breaker 103includes a recess 108 formed in a front portion, for reception of arespective tab 107 when mounted on the chassis 101, for support.

A series of cross-rails or bus isolators 109 extend between the breakermounting rails 106 to mount three feed buses 110, as for example byscrew 111, washer 112 combinations threadibly received through alignedopenings 113, 114 formed in the feed buses 110 and cross-rails 109,respectively, as illustrated in FIG. 7. Each feed bus 110 corresponds toone phase of a three phase system which can be, e.g., a three phase120/208 volt, 4 wire Y service. The bus isolators 109 are made from anelectrical insulator material and the feed busses 110 are made from anelectrical conductor such as, e.g., copper.

Each feed bus 110 includes a series of connector link openings 115formed along the length thereof. A plurality of generally invertedU-shaped connector links 116 are mounted to the middle feed bus 110. Tothat end, each connector link 116 includes a pair of outwardly extendingportions 117, each provided with an opening 118 arranged to align withone of the openings 115 of the middle feed bus 110. Screws 119,e.g.,self taping hex head screws, are used to secure each connector link116 to the middle feed bus 110. Each connector link 116 is formed toinclude a pair of breaker connector openings 116a.

Likewise, a series of generally planar connector links 120 are securedto each outer feed bus 110 by screws 119, each received through arespective opening 121 formed in each connector link 120 and alignedwith one of the openings 115 of a respective outer feed bus 110. Eachconnector link 120 includes a raised portion 122 extending from therespective outer feed bus 110 to a position aligned over the middle feedbus 110. Each raised portion 122 includes a pair of breaker connectoropenings 120a.

The generally inverted U-shaped connector links 116 and generally planarconnector links 120 are arranged, relative to one another, to provide analternating sequence of breaker connector opening pairs 116a, 120aaligned with and spaced along the middle bus feed 110. Moreover, eachpair of breaker connector openings 116a, 120a is aligned with a pair oftabs 107, one on each breaker mounting rail 106. Each circuit breaker103 includes a terminal 130 having an opening 130a such that the circuitbreaker 103 can be removably mounted to the chassis 101 by applying therecess 108 of the circuit breaker 103 over one of the tabs 107 of arespective breaker mounting rail 106, for support, and screwing theterminal 130 to one of the pair of breaker connector openings 116a, 120aaligned with the respective tab 107, with a screw 131.

As should be understood, the above-described chassis 101 will removablymount a plurality of circuit breakers 103 within the interior of thecabinet, in two side-by-side arrays, due to the plurality of tabs 107and aligned pairs of breaker connector openings 116a, 120a. Eachconnector tab 116, 120 forms an electrical connection between eachrespective circuit breaker terminal 130 and one of the feed buses 110.For one phase service, e.g., 120/240 volt, 3 wire service, the middlefeed bus 110 can be removed from the chassis 101.

As illustrated in FIG. 7, each circuit breaker 103 includes a switch 23that is accessible to a user through the use of the hinged panel door 21(See FIG. 2), as described above. In addition, each circuit breaker 103is provided with a second terminal 132 for selective coupling to one ofthe connectors, e.g., one of the connectors 19 mounted on side panels 15(See FIGS. 1 and 6), such that each connector 19 is selectively coupledto one of the feed buses 110 via a respective circuit breaker 103, forindividual overcurrent protection for a branch load supplied by theconnector 19.

Two pole circuit breakers can also be mounted on the chassis 101. Eachtwo pole circuit breaker would align with and be mounted to two adjacenttabs 107 and connect to two of the feed busses 110. Two pole circuitbreakers would be used to supply a higher voltage branch load, ifdesired. Likewise, three pole breakers can be mounted to the chassis 101for a three phase connection to a branch feed connector to energize,e.g., a delta motor load. Thus, the chassis 101 provides flexibility inthe type of circuit breaker 103 that can be removably mounted withineach cabinet 10.

Each feed bus 110 is arranged to extend beyond the outer cross-rails 109and is provided with openings 133 for coupling to the bus feedarrangement 100. Referring now to FIG. 6, an L-shaped bus connector 150is received upon the end of a respective feed bus 100 extending beyondthe outer cross-rail 109. The L-shaped bus connector 150 includesopenings arranged to align with the openings 133 of the respective feedbus 110 for secure mounting thereon, as for example, by screws 151. Theterminal 102 of each one of the three connectors 18 corresponding to thethree phases of the three phase system, is connected to a bus feed 152,by a nut 153. Each one of the bus feeds 152 extends to a correspondingL-shaped bus connector 150 and is secured thereto by screws 154.

Accordingly, the bus feed 152, L-shaped bus connector 15 arrangementelectrically couples each one of the feed buses 10 to a correspondingconnector 18. Thus, each connector 18 can be coupled to a source ofelectric power by a plug-in cable, as described above, to energize thethree feed buses 110, and through the breaker tabs 116, 120 andterminals 130, energize each second terminal 132 of each circuit breaker103 mounted within the circuit breaker chassis 101.

The terminal 102 of the fourth connector 18 is secured to an L-shapedbus connector 155 by a nut 153, and the L-shaped bus connector 155 is,in turn, secured to a neutral bus 156, e.g., by a pair of screws 157.The neutral bus 156 is mounted in a raised position above the bottompanel 17 by insulator posts 157 and extends around the end and two sidesof the circuit breaker chassis 101. One or more electrically conductiveconnector strips 158 are mounted on the neutral bus 156. Each of theconnector strips 158 includes a plurality of individual connectoropenings 159 to provide a neutral coupling for each side panel mountedconnector 19, as will appear.

Furthermore, the terminal 102 of the fifth connector 18 mounted on theend panel 13 is connected to another L-shaped bus connector 160 by a nut153. The L-shaped bus connector 160 is fastened to the bottom panel 17to provide a common ground within the cabinet 10 that can be coupledthrough the fifth connector 18 to the common ground of other cabinets 10and the ground of the source of power, e.g., a generator. Moreover, oneor more connector strips 161 are mounted to the bottom panel 17. Each ofthe connector strips 161 includes a plurality of individual connectoropenings 162 to provide a ground coupling for each side panel mountedconnector 19, as will appear.

For illustration purposes, a single connector 19 is depicted in FIG. 6.However, it should be understood that several connectors 19, of anydesired type can be mounted to the side panels 15 for connection tobranch circuits. In addition, the circuit breaker chassis 101 isarranged to mount one circuit breaker 103 for each connector 19.

As illustrated, the connector 19 includes three leads 165, 166, 167arranged to extend into the interior of the cabinet 10 when the panel 15mounting the connector 19 is secured to the cabinet 10. The first lead165 is selectively coupled to a connector 132 of one of the circuitbreakers 103, the second lead 166 is selectively coupled to one of theconnector openings 159 of the connector strip 158 mounted on the neutralbus 156 and the third lead 167 is coupled to one of the connectoropenings 162 of the connector strip 161 mounted on the bottom panel 17for a ground connection. Thus, the connector 19 in this example iseasily coupled to one phase of the three phase system, the neutralterminal of the three phase system and to the common ground and includesa circuit breaker 103 for individual overcurrent protection. Of course,when two pole or three pole breakers are used, the branch connectorscould have three or four leads for connection to two or three connectors132 of a two pole or three pole circuit breaker, respectively, forconnection to two or all three phases of the three phase system toprovide various voltage outputs from the three phase system.

The removable coupling of the leads 165-167 facilitates easydisconnection of each connector 19 from the circuit breaker 103, neutralbus 156 and ground 161 when the panel 15 mounting the connector is to beremoved for installation of another panel 15 mounting a different typeof connector. Likewise, each circuit breaker 103 is easily removed andreplaced within the breaker chassis 101.

The cabinet 10 depicted in FIG. 6 is arranged as a branch feed typecabinet. Referring to FIG. 6a, there is illustrated a top plan view of acabinet 10, similar to the cabinet of FIG. 6, except that the cabinet 10depicted in FIG. 6a includes a five connector 18, bus feed 100arrangement installed on each end panel 13 of the cabinet 10, to providea trunk feed type cabinet. A series of such trunk feed type cabinets 10can be arranged as trunk feeds in a network. For example, the connectors18 on one end panel 13 can be female type plug-in connectors and theconnectors 18 on the other end panel 13 can be male type plug-inconnectors such that flexible cables, having male and female ends, cancouple the trunk feed type cabinets in series.

Referring now to FIG. 6b, there is illustrated a cabinet 10 arranged asa main power feed cabinet. A main circuit breaker 200 is mounted withinthe cabinet 10 on bottom panel 17, as for example by a nut and boltarrangements 201. One end panel 13 is provided with five connectors 18coupled to a feed bus arrangement 100, as in the cabinet illustrated ineach of FIGS. 6 and 6a. The buses 152 from three connectors 18 are eachcoupled to an L-shaped connector 150, which is in turn, mounted on anoutput bus bar 202. Each output bus bar 202 is coupled to one output ofthe three phase output of the main circuit breaker 200. Each output busbar 202 can be mounted on insulator posts, secured to the bottom panel17, for support (not specially illustrated).

A neutral connector 203, also supported on an insulator post secured tothe bottom panel 17, is coupled to the L-shaped bus connector 155connected to a forth one of the connectors 18, acting as a neutralterminal, as described above. Furthermore, similar to the embodiment ofFIGS. 6 and 6a, a fifth connector 18 mounted on the end panel is coupledby L-shaped ground connector 160 to the bottom panel 17.

Accordingly, the five connector 18, feed bus arrangement 100 of the endpanel 13 provides connectivity to one of the trunk type cabinets 10, asillustrated in FIG. 6a, to provide a source of power to a networkcoupling trunks and branches formed by the cabinets 10 of the typesillustrated in FIGS. 6 and 6a.

The opposite end panel 13 of the main power feed cabinet 10 is providedwith a generally cylindrical, hollow power conduit 204 to insert a mainpower feed from, e.g., a public utility source or a power generator (notspecifically illustrated). The individual phase cables of the main powerfeed can be coupled to the three phase inputs of the main circuitbreaker 200, and the neutral cable can be coupled to the neutralconnector 203. The cabinet 10 itself can be grounded to a common groundwith the source of power, which ground connection is connectedthroughout the network via the connector 160, fifth connector 18arrangement of each cabinet 10, as illustrated in FIGS. 6, 6a and 6b.

A bracket 205 can be mounted within the cabinet 10 to support, e.g.,indicator lights indicative of the operation of the network, if desired.

Referring now to FIG. 8, there is depicted a block diagram of an exampleof a network comprising several cabinets according to the presentinvention. Each type 1-7 for the cabinets 10 corresponds to the type,quantity and power characteristics of the connectors mounted in the sideand end panels, as indicated on the drawing of FIG. 8. As should beappreciated, any configuration for the network and any type ofconnectivity for each main power feed, trunk and branch cabinet 10within the network is readily achievable due to the modular constructionof the cabinet according to the present invention. Moreover, eachcabinet 10 will be light-weight, durable and of a high structuralintegrity.

Referring now to FIGS. 9-14, there is illustrated a portable powerdistribution cabinet according to the present invention arranged with adirect access panel to permit the direct coupling of lugged cables tothe feed busses 100 of the cabinet 10. As shown in FIG. 9, the switchhousing 22 is provided with an opening 250 for direct access to each ofthe busses 110, neutral bus 156 and L-shaped ground connector 160mounted within the cabinet 10. In this manner, set screws 303 of lugs301, as, e.g., sister lugs, soldered to cables 300 can be reached tofasten the lugged cables 300 to the appropriate busses or groundconnection without having to remove any panels from the cabinet 10, aswill appear.

The hinged door 21 is ordinarily closed to isolate the interior of thecabinet 10 and thereby prevent exposure to the electrical connectionswithin the cabinet 10. Moreover, a transparent plastic panel 251 ismounted within the opening 250 to prevent electric shock hazard when thehinged door 21 is open. The transparent panel 251 can comprise a Lexan®window to provide a heavy duty, heat resistant, transparent window forshock prevention. however, the transparency of the Lexan® window 251will enable a worker to view the lugged cables 300, busses 110, 156 andground connection 160.

The transparent panel 251 is formed to include a plurality of relativelysmall diameter holes 252. Each one of the holes 252 is aligned with oneof the set screws 303 of one of the sister lugs 301 when thecorresponding cable 300 is inserted into the cabinet 10, as will bedescribed below. The diameter of each hole 252 is dimensioned so thatthe worker can insert a tool, such as an Allen tool, therethrough toengage the aligned set screw 303 and thereby secure the cable 300 to therespective bus 110, 156 or ground connection 160. Accordingly, theopening 250, transparent panel 251 arrangement provides a full view ofthe lugged cables 300, busses 110, 156 and ground connection whileisolating a worker from electric shock hazard and permitting access fora tool for engagement with the set screws 303.

As illustrated in FIGS. 10 and 11, the interior of the cabinet of FIG. 9is modified to accommodate the direct coupling of lugged cables to thebus arrangement. The interior of the cabinet 10 illustrated in FIG. 10is generally similar to the interior of the cabinets 10 shown in FIGS.6, 6a and 6b, with like reference numerals corresponding to the samecomponents. However, in the cabinet 10 of FIG. 10, each of the feedbuses 110, the neutral bus 156 and L-shaped common ground connector 160is arranged to extend within a U-shaped cable guide 275 mounted to thebottom panel 17 by insulated bushings 276 (See FIG. 11). Each of thebuses 110, 156 and ground connector 160 is secured to a respective cableguide 275 by a screw 277 received through each of an insulated spacer278 and the respective cable guide 275 and threaded into one of theinsulated bushings 276, as illustrated in FIG. 11. In this manner, whena power cable 300 is inserted into the cabinet 10, as will be describedin more detail with reference to FIG. 13, it will be received into arespective one of the cable guides 275 for guided movement toward acorresponding one of the buses 110, 156 or ground connector 160.

As described above, each power cable 300 is provided with a sister lug301 having a set screw 303. The sister lug 301 is also formed to includea U-shaped opening 302. The U-shaped opening 302 of each lug 301 isdirectly received over a respective one of the buses 110, 156 or groundconnector 160 and the set screw 303 is turned until it mechanicallysecures the lug 301 for an electrical connection with the respective bus110, 156 or ground connector 160, as illustrated in FIG. 11. As shouldbe understood, the opening of the hinged panel 21 exposes the sisterlugs 301 through the holes 252 of the transparent panel 251 forplacement and securing or removal of the power cables 300 to or from thebuses 110, 156 or ground connector 160, as the case may be (See alsoFIG. 9).

FIGS. 12 and 13 illustrate a direct access end panel 13a mounted to thecabinet 10 for direct coupling of lugged cables 300 to the interior busarrangement of the cabinet 10. The direct access end panel 13a isprovided with a cable clamp door 320 rotatably mounted to the panel 13aby a piano hinge 321. As shown in FIG. 12, the cable clamp door 320 isfixed in a closed position by a pair of threaded studs 322. When in theclosed position, a U-shaped lower end 323 of the door 320 engages andclamps the cables 300 against a neoprene gasket 324 that is mountedalong a metal stress angle strip 325 fixed to the end panel 13a. Theclearance between the end 323 of the door 320 and the gasket 324 isfixed so that the clamping action on the cables 300 is sufficient tohold the cables 300 against any mechanical forces as would likely beencountered in the operating environment of the cabinet 10. Thus, theengagement between the end 323 of the door 320, the cables 300 and thegasket 324 of the stress angle strip 325 provides stress relief tomechanical forces applied to the cables 300 during use of the cabinet10. Accordingly, such mechanical forces will not be applied directly tothe set screws 303 of the cables 300 to maintain the integrity of theelectrical connections. Moreover, in the event of a solder meltdown dueto an electrical overload or arcing caused by a loose connection, thecables 300 will be maintained in a fixed position by the clamping actionof the door 320.

As shown in FIG. 13, the direct access end panel 13a is formed toinclude a plurality of openings 326, one for each cable 300. Each one ofthe openings 326 is aligned with one of the U-shaped cable guides 275 sothat when a cable 300 is inserted into the opening, it is received intothe corresponding cable guide 275 for guided movement toward arespective bus 110, 156 or ground connection 160 for connection, asdescribed above.

Referring now to FIG. 14a, there is illustrated a side cross-sectionalview of the direct access end panel 13a of FIGS. 12 and 13, with thethreaded studs 322 removed and the cable clamp door 320 in an openposition. The end panel 13a is provided with a pair of threaded openings327 (only one illustrated). Moreover, a pair of slots 328 (only oneillustrated) is formed in the cable clamp door 320 and each of the slots328 is positioned to be aligned with a corresponding one of the threadedopenings 327 of the end panel 13a when the door 320 is in the closedposition. In this manner, each of the threaded studs 322 can be receivedthrough one of the slots 328 and threaded into the corresponding alignedthreaded opening 327 to secure the cable clamp door 320 in the closed,cable clamping position (See FIG. 14B).

When the cable clamp door 13a is in the open position, each cable 300 iseasily inserted through a preselected one of the openings 326 forcoupling to a corresponding bus 110, 156 or ground connector 160 (SeeFIGS. 9 and 10) via a tool inserted through the respective hole 252 ofthe transparent panel 251 exposed by the hinged panel 21. Once thecables 300 are coupled to the buses 110, 156 and ground connector 160,each of the hinged panel 21 (FIG. 1) and the cable clamp door 320 isclosed (FIG. 14B). The threaded studs 322 are then threaded into thethreaded openings 327 to secure the cable clamp door 320 in the closed,cable clamping position.

The direct access end panel 13a of the present invention provides aconvenient, labor efficient device for direct coupling of lugged cables300 to the bus arrangement within the cabinet 10. The hinged cable clampdoor 320 simultaneously clamps all of the cables 300 inserted throughthe openings 326 of the end panel 13a in one operation for ancillarystress relief. In addition, the dimensions of the openings 326 can bearranged so that the placement of the closed door 320 substantiallyseals the interior of the cabinet 10.

What is claimed is:
 1. A stress relief device for a cable-like element,which comprises:a panel forming an opening for passage of the cable-likeelement therethrough; and a door rotatably mounted to the panel forrotation between an open position and a closed position and arranged sothat the door is clear of obstruction of the opening when in the openposition and partially obstructs the opening when in the closedposition; each of the panel and the door being dimensioned relative toone another so that said door engages and clamps the cable-like elementagainst said panel when the cable-like element is passed through theopening and the door is in the closed position.
 2. The stress reliefdevice of claim 1, wherein the door is hingedly connected to the panel.3. The stress relief device of claim 1 further comprising a fastener forsecuring the door in the closed, cable clamping position.
 4. The stressrelief device of claim 3, wherein the fastener comprises a threadedstud, the door is formed to include a slot opening for reception of thethreaded stud and the panel is formed to include a threaded openingaligned with the slot opening of the door when the door is in the closedposition for threaded engagement with the threaded stud to fasten thedoor in the closed position.
 5. The stress relief device of claim 1,wherein the door is formed to a U-shaped end for clamping engagementwith the cable-like element when the door is in the closed position. 6.The stress relief device of claim 5, wherein the panel is formed toinclude a stress angle strip for supporting the cable-like element whenthe element is passed through the opening.
 7. The stress relief deviceof claim 6 further comprising a gasket mounted on the stress angle stripfor supporting the cable-like element when the element is passed throughthe opening.
 8. The stress relief device of claim 1, wherein the panelforms a plurality of openings for passage of a plurality of cable-likeelements, one through each of the plurality of openings, and wherein thedoor partially obstructs all of the openings when in the closed positionto simultaneously engage and clamp the plurality of cable-like elementsagainst said panel when the cable-like elements are passed through therespective openings and the door is in the closed position.
 9. Aportable power distribution cabinet, which comprises:side, end, top andbottom panels connected to one another to form an enclosure; a pluralityof electrical conductors mounted within the enclosure; the electricalconductors including power input and output conductors adapted fordirect coupling to lugged cables; one of the panels forming a pluralityof openings for passage of lugged cables therethrough, one of the luggedcables per opening, for passage of the lugged cables into the enclosurefor direct coupling of the lugged cables to the power input and outputconductors; a door rotatably mounted to the one panel for rotationbetween an open position and a closed position and arranged so that thedoor is clear of obstruction of the openings when in the open positionand partially obstructs the openings when in the closed position; eachof the one panel and the door being dimensioned relative to one anotherso that said door simultaneously engages and clamps the lugged cablesagainst said one panel when the lugged cables are passed through therespective openings and the door is in the closed position.
 10. Theportable power distribution cabinet of claim 9 further comprising aplurality of cable guide channels mounted within the enclosure, each ofthe cable guide channels being arranged and configured to extend betweenone of the openings of the one panel and one of the power input andoutput conductors, so that lugged cables passed through the openings arereceived into a corresponding cable guide channel for guided movement toa respective one of the power input and output conductors.
 11. Theportable power distribution cabinet of claim 9, wherein the enclosureincludes a rotatable cabinet door panel for access to the interior ofthe enclosure for coupling the lugged cables to the power input andoutput conductors.
 12. The portable power distribution cabinet of claim11, further comprising a transparent panel mounted beneath the rotatablecabinet door panel to isolate the interior of the enclosure when therotatable cabinet door is rotated for access to the interior of theenclosure; the transparent panel being formed to include small diameterholes for insertion of a tool to engage the lugged cables for couplingto the power input and output conductors.